1. Field
One embodiment of the invention relates generally to an electronic apparatus such as a personal computer, and more particularly to an electronic apparatus including two electronic components which are interconnected by a flexible flat cable.
2. Description of the Related Art
In general, in the field of electronic apparatuses such as a personal computer and a communication apparatus, flexible flat cables (FFC) are widely known as mechanisms for interconnecting electronic components. The flexible flat cable can easily connect electronic components by virtue of its high flexibility. Normally, the flexible flat cable is composed of a plurality of conductors which are interposed between two insulation layers.
Recently, the flexible flat cable has begun to be also used for transmission of high-speed signals. Jpn. Pat. Appln. KOKAI Publication No. 2003-217360 discloses a flexible flat cable which includes a dedicated ground layer which is used for impedance matching of signal lines in the flexible flat cable. The flexible flat cable comprises a plurality of signal lines which are arranged on the front surface of an insulation layer, a ground layer which is provided on the back surface of the insulation layer, and drain wires which are in contact with the ground layer. In the vicinity of an end portion of the flexible flat cable, the drain wires are led out from the lower surface side of the insulation layer to the upper surface side of the insulation layer, and are put in contact with two signal lines (ground lines) which are positioned on both outer sides of the plural signal lines.
In the structure of the flexible flat cable of the above-described KOKAI Publication No. 2003-217360, however, dedicated through-holes for leading the drain wires from the lower surface side of the insulation layer to the upper surface side of the insulation layer have to be provided in the insulation layer. This considerably increases the manufacturing cost of the flexible flat cable.
In the meantime, in usual cases, not only high-speed signals, but also ordinary signals that require no high speed transmission, as well as a ground potential and a positive power supply potential, are transmitted through the flexible flat cable that interconnects two electronic components. In this case, a signal line, which requires exact impedance matching, is only the signal line that is used for transmission of high-speed signals. It is necessary, therefore, to realize a novel cable structure for securing high-speed transmission characteristics with respect to only the signal line for transmitting high-speed signals.
In addition, as regards the flexible flat cable, it is necessary to make some devices for facilitating an assembling work of an electronic apparatus and a reassembling work after repair of an electronic apparatus.